Data is frequently transferred between devices, such as personal computers, workstations, mainframes, supercomputers, storage devices, and servers, using a data transfer protocol and interface system, such as Fibre-Channel. Fibre-Channel technology involves coupling various devices together with optical fiber or a Fibre-Channel compatible electrically conductive (copper) cable. Fibre-Channel allows extremely rapid data transmission speeds between devices separated by relatively great distances.
Fibre-Channel is commonly configured in what is referred to as a Fibre-Channel Arbitrated Loop (FC-AL). In an arbitrated loop system, ports arbitrate for use of the loop. Once a port, e.g., referred to as an L-port, wins the arbitration based on its lowest port address, for example, a second L-port is opened up to complete a single bidirectional point-to-point circuit between the two L-ports. Only one pair of L-ports may communicate at one time. When two connected ports release control of the loop, a point-to-point circuit can be established between two other ports on the loop.
One application involves using an FC-AL to provide connectivity between blades of a bladed server. Bladed servers are comprehensive computing systems that include a processor, memory, network connections, and associated electronics all on a single or multiple circuit modules called server blades, for example. In addition, bladed servers often include other blades, such as server appliance blades, network-switch blades, storage blades, management blades, local-area-network-(LAN-) blades, etc. The various blades are usually electrically connected to a backplane of the bladed server.
The FC-AL is sometimes implemented using a port bypass circuit blade that is also electrically connected to the backplane. The port bypass circuit blade includes a number of port bypass circuits and embedded software or firmware for implementing the FC-AL. In this arrangement, each of the blades is connected to one of the port bypass circuits via a port of the port bypass circuit blade. One problem with this is that port bypass circuit blades normally do not provide more than one or two retiming elements, normally used to provide reconditioned data signals that comply with Fibre-Channel signal quality specifications. This means that data signals cannot be reconditioned at each of the ports of the port bypass circuit blade before being respectively transmitted to each of the blades. FC-AL switches with multiple ports having retiming at each of the multiple ports are available for a variety of applications. However, FC-AL switches normally do not have enough ports for bladed server applications.
For the reasons stated above, and for other reasons stated below that will become apparent to those skilled in the art upon reading and understanding the present specification, there is a need in the all for alternative Fibre-Channel implementations.